Due to their sessile nature, plants are constantly under the threat of temperature stress when they are subjected to a wide range of temperature variation in different habitats and climates during growing seasons and even diurnally. Most economically valuable plants, including those used in agriculture, horticulture, forestry, biomass for bioconversion, and other industries (e.g., the paper industry or pharmaceutical/chemical industries where plants are used as production factories for proteins or other compounds) are exposed to higher than optimal temperatures, or heat stress, during some stages of their life cycle from seed germination to seed maturation (Maestri et al. Plant Mol. Biol. 48:667-681 (2002)). Heat stress is one of the most common stresses in crop production. Under heat stress, plants can succumb to a variety of physiological and developmental damages, including dehydration due to increased transpiration, impairment of photosynthetic carbon assimilation, inhibition of translocation of assimilates, increased respiration, reduced organ size due to a decrease in the duration of developmental phases, disruption of seed development, and a reduction in fertility (Berry and Bjorkman, Ann. Rev. Plant Physiol. 31:491-543 (1980); Cheikh and Jones, Plant Physiol. 106:45-51 (1994)). Thus, exposure to heat stress often results in reduced yield and overall decreased crop quality (Maestri et al. Plant Mol. Biol. 48:667-681 (2002)).
In the field, heat stress is often associated with other stresses, such as drought and high light, which presents even greater challenge to plants. Plants exposed to low water or drought conditions typically have low yields of plant material, seeds, fruit and other edible products. Some areas of the world consistently have very low rainfall and therefore have problems growing sufficient food crops for their population.
Thus, there is a need for methods of increasing drought and/or heat tolerance in plants.